The present invention is directed to chemically treated glass fibers, strands or yarn where the fibers impart improved strength in reinforcing polyolefins.
Glass fibers are produced by flowing molten glass via gravity through a multitude of small openings in a precious metal device, called a bushing. Typical formulations of glass fibers are disclosed in K. Loewenstein, The Manufacturing Technology of Continuous Glass Fibres, (3d Ed. 1993).
After the fibers have cooled very shortly after their issuance from the bushing and usually in close proximity to the bushing, these fibers are treated with a chemical treating formulation usually referred to in the art as a sizing composition, sizing, or size. The sizing composition serves to make the fibers more compatible with the material they will ultimately be used to reinforce and to make the fibers more easy to process. The sizing composition can be applied by sprayers, rollers, belts, metering devices or any similar application device. The sized glass fibers are gathered into bundles or strands comprising a plurality of individual fibers, generally from 200 to more than 4000.
After their formation and treatment, the strands can be wound into a spool or “forming package” and/or may be chopped. The forming packages or chopped strands are usually dried in either an oven or at room temperature to remove some of the moisture from the fibers. Strands from the forming packages may also be wound into rovings.
The strands of treated fibers can be used to reinforce various materials such as thermoplastic polymers and thermosetting polymers. One example of a commercially important use of treated fibers is to reinforce olefinic thermosetting polymers, especially polymers of cycloolefins. It would be desirable to have commercial fiber glass materials that are effective reinforcements for cycloolefinic resins that cure by the ring-opening metathesis polymerization (“ROMP”) reaction. In particular, it would be desirable to have commercial fiber glass materials that are effective reinforcements for polymers formed from dicyclopentadiene (“DCPD”) monomer.
There is a growing need for an effective fiber glass reinforcement for DCPD resins. These resins have a number of advantages over more conventional thermoset resins, especially the widely used polyester resins that have styrene as a co-monomer and diluent. As environmental controls become more stringent on VOC's, a cost-competitive, low viscosity (needed for fast wetting of glass fibers) resin system that cures without styrene co-monomer/diluent is desirable.